robt964

Here you go - the parts were easy to get to than I thought :-)

Rear alumnium bumper beam -> 5.1kg
Rear bumper beam mounting tubes-> 0.8kg (pair)
Engine undertray -> 4.7kg

I'd throw in 0.5kg for the bolts and fixings for that lot.

Captain Ahab Jr.

after much cussing, a bit of head scratching and some spilled claret I removed a few other parts tonight and hit a milestone of removing the first 50kgs

0.279kg heating donkey dick from dash to cill inc. jubilee clips, pair
0.106kg plastic sill vents below rear side window, pair
1.961kg heating donkey dick insulated ducting inside the cill, pair

previously removed but now added with weights from robt964, thank you sir

5.100kg rear bumper aluminium beam (not inc. fixings)
0.800kg rear bumper beam mounting tubes, pair (not inc. fixings)
4.700kg engine under tray (not inc. fixings)

Weight removed running total 52.369kg

I'm enjoying the whole process of stripping this car down to the minimum needed, still so much stuff to remove, finding it very theraputic really clears the mind after a day of work

robt964

So you're running with no heat then?

Captain Ahab Jr.

For the moment yes.

Will try an electric heated windscreen at a later stage of the build.

I'd rather remove too much than keep something I think I might need, if I miss it then I'll refit it.

Captain Ahab Jr.

My list of 30 something bits to remove is getting longer everytime I poke around the car, think I can hit 100kgs before I have to start cutting bits out and changing parts for lighter versions.

Tonights efforts,

0.258kg set of 4 wheel centre caps (not orginal Porsche parts)
1.550kg passenger seat electrical motors, drive cables, wiring loom and steel mounting bracket
0.024kg cigarette lighter
0.285kg ashtray and dash holder
0.895kg pair of rear floor carpets
0.055kg diagnostic plug steel mounting bracket

Weight removed running total 55.463kg

HiWind

Are you running the OEM seat? It sounds like you're going the stay stock but remove dead weight route, but every time I switch seats for track days it blows my mind how different the weight of stock sports vs gt3 seats are. If you're going to 'cheat' that's where. Oh and the exhaust - decat, mufflers etc... Recon those can get you to 80.

Captain Ahab Jr.

Thanks for the suggestions HiWind

A pair of Porsche 4 way electric seats weighs 46kg/101.4lbs pair + wiring harnesses

Need to keep access to the back seats for now so the stock front seats will stay. For sure I will replace them with something lighter but until then its a few kgs in the bank.

Just saved another 0.1kg/3.5oz on the pair of front seats by removing a bolt from one of three holding on each motor and one from the rear where the seat slide mounts to the chassis

Also had a poke about the exhaust, would appear I have no centre muffler just a straight through pipe.

My car is an Aug. 1990 Euro build so would the straight through pipe replaced a centre muffler or cat and what would the weight saving be with this mod?

Metal Guru

I wouldn't do that.
In a head-on crash the seat tracks could rip out of the floor without the proper number of bolts, with the end result of the occupants being tossed around the interior and suffering catastrophic injuries.
The risk isn't in the same solar system when weighed against the benefits.

HiWind

+1 ... Rear shd be two bolts on each runner else You're flippin this coin:
Head I win a tiny amount, tails I loose alot

PeterS911

+2

That's just barmy. If you wear a cap, you've added more weight than you've taken away by risking your safety.

And on that subject, what do you weigh now, and what do you aim to weigh at the end? Lets face it, it's the combined weight that counts.

StanUK951

I think he's removed a bolt from the seat motor, not the slider rails, if you read it properly guys.

Scratch that. Just re-read it again myself! Surely not worth removing this for such a tiny minuscule saving when you're keeping the heavy Recaro seats anyway! Shouldn't you start with the big stuff first?

Captain Ahab Jr.

Guys, thanks for raising your concerns but I don't think what I've done by removing these bolts is not going to cause myself anymore risk of damage.

Looking at the extra rear bolt I'm not sure I can see a reason for it with regards impact safety,

In a head on crash, a very high percentage of the impact load will be taken through the seat belt mountings mountings as there is no seat support to stop you sliding forward

In a side impact, as the seat has no high side supports so again there is little load going through the seat to chassis fixings

In a rear impact the two rear fixings would be in compression as the seat back is angled rearwards, in this load case the single front fixing would be tension which would fail first

Add multiple combinations of these as the occupants are thrown about the car and I still see no reason for the extra bolt.

To me the most obvious reason for the rear extra bolt is to prevent any distortion of the seat rail if a rear passenger was to fall forward on to the tilted forward seat while climbing out of the back. The extra bolt is just there to spead out the load instead of it acting on a single point which could locally distort the seat rail and bind up the sliders. If anyone has any other ideas why Porsche used this extra bolt then I'm quite happy to be corrected

I had a quick look around on this excellent forum and found this

check out post #25 by Cupcar showing a picture of the Porsche Motorsport Recaro OEM SPG mounting as used in the 964 Cup cars
https://rennlist.com/forums/964-foru...details-2.html

or joey bogonuts post #56 showing an exploded view of the 964 Speedester seat mounting assy

Just to be on the safe side I'll also get a 2nd opinion from a friend who has build WRC cars and 3ed opinion from another friend who works in the stress department in a F1 team

Also I agree there are plenty of bigger fish to fry if I want to save weight and I include myself on that list but my aim with the first stage of this build is to see how much weight can be lost from a standard 964 C2 by just unbolting parts. Promise it will get more interesting later on.

Metal Guru

Think of it this way: in a crash, the car suddenly decelerates, however, you, strapped to the seat, are still traveling at velocity x with the momentum of your mass and the mass of the seat. Those little, soft bolts (yes, I said soft; I've stripped enough of them to know) have to keep you and that seat anchored to the chassis.
Another consideration is this: crashes are highly variable events. Crash testing has demonstrated this time and again. Manufacturers only do as many tests as they can get away with. Why? Because every time they crash a vehicle, no matter how carefully they try to duplicate the set-up, they find a new issue.
But, hey, it's your butt. You do what you want.

Captain Ahab Jr.

the quest continues, after a fruitful day

9.332kg rear seat area and rear foor sound deadening (not including rear bullkhead area)
0.220kg carpet behind rear sear bases
0.609kg pair of carpets outboard of rear seat bases
0.232kg pair of carpets below and forward of rear seat bases
1.171kg pair of leather seat bases
6.170kg pair of leather seat backs including outboard bolt (not including centre sprung pin bracket, will add this to the weight as I forgot)
0.742kg sunroof air defelector, front sunroof metal surround
0.182kg plastuc outer sill protectors
2.098kg pair of rear seatblets including mounting bolts/washers

Weight removed running total 76.219kg/168lbs


Top tip: if cleaning off all the sound deadening glue while wearing shorts be sure to shave you legs before, it will save you a lot of pain later

STUARTQ

Just bringing the seat fixing issue back.
On the 964, there is a seat belt mounting point for the buckle. If you are using a full harness and the mounting points are body mounted, then I see no issue at all from removing these 2 bolts. If, however, the standard seatbelts are used, I would not compromise and reinstate those bolts.
Over the last 20 years I have been involved in many seatbelt and other passenger and equipment dynamic tests and it never seases t o amaze me that something tried and tested can so easily fail when the parameters are changed only slightly.